N2O emission from a temperate forest soil during the freeze-thaw period: A mesocosm study
N2O emission from a temperate forest soil during the freeze-thaw period: A mesocosm study
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冻融期间温带森林土壤的 N2O 排放：中生态系统研究
DOI：
10.1016/j.scitotenv.2018.08.155
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发表时间：
2019-01-15
影响因子：
9.8
通讯作者：
Bai, Edith
中科院分区：
文献类型：
--
作者：
Peng, Bo;Sun, Jianfei;Bai, Edith
一氧化二氮（N2O）是一种重要的温室气体，与臭氧层的破坏有关。然而，冻融期土壤N2O排放的机制尚不清楚。本文采用高频原位观测的方法，研究了围隔生态系统中土壤微生物对FT循环的响应及其对土壤N2O排放的影响。结果表明，冻结期N2O的释放主要是由于基质的释放、冻结期酶活性的维持以及解冻期微生物生物量氮（MBN）的快速恢复和微生物活性的提高。物理隔离以前产生的N2O是一个重要的机制，较高的N2O通量在解冻阶段。随着FT循环次数的增加，解冻期MBN保持稳定，解冻期潜在脱氢酶活性在前8个FT循环后保持稳定，仅在最后2个FT循环期间下降，表明生物学机制的可持续性。研究表明，尽管MBN有所下降，但微生物酶在零下几摄氏度仍能保持较高的活性，即使在冻结期也能产生较高的N2O通量，这些通量被截留在冰层下，在解冻期释放，导致FT期土壤N2O排放量较高。(C)2018爱思唯尔B.V.保留所有权利。
Nitrous oxide (N2O) is an important greenhouse gas and is involved in the destruction of ozone layer. However, the underlying mechanisms of the high soil N2O emission during the freeze-thaw (FT) period are still unclear. Here, we conducted a mesocosm study with high frequency in situ measurements to explore the responses of soil microbes to the FT cydes and their influences on soil N2O emission. We found the high N2O emission rate during the FT period was mainly due to the release of substrates, the maintenance of high enzyme activities at the freezing stage, and the fast recovery of microbial biomass nitrogen (MBN) and high microbial activities at the thawing stage. Physical isolation of previously produced N2O was an important mechanism for the higher N2O flux at the thawing stage. With increasing numbers of the FT cydes, MBN at the thawing stage remained stable and potential dehydrogenase activities at the thawing stage also remained stable after the first eight FT cydes and only declined during the last two cycles, suggesting the sustainability of the biological mechanisms. Our study suggests that although MBN declined, microbial enzymes could maintain high activities at a few degrees Celsius below zero in this temperate forest soil and produce high N2O fluxes even at the freezing stage, which were trapped under the ice layer and released at the thawing stage, resulting in high soil N2O emission during the FT period. (C) 2018 Elsevier B.V. All rights reserved.